System and method for building climate control

ABSTRACT

A method of controlling the climate of a building includes determining a difference between a current aspect of a climate in a building and a set point for the aspect of climate in the building for one or more zones of the building, summing the differences at a climate system controller, and determining a set point for one or more operating variables of one or more components of a climate system in the building based on the sum of the differences. A climate system for a building is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application No.62/839,497, filed on Apr. 26, 2019, which is incorporated by referenceherein in its entirety.

BACKGROUND

Buildings, such as university buildings, office buildings, residentialbuildings, commercial buildings, and the like, include climate systemswhich are operable to control the climate inside the building. Somebuildings have climate requirements which vary over time. The climatesystems are operable to maintain a desired climate the in building.

SUMMARY

A method of controlling the climate of a building according to anexemplary embodiment of this disclosure, among other possible thingsincludes determining a difference between a current aspect of a climatein a building and a set point for the aspect of climate in the buildingfor one or more zones of the building. The method also includes summingthe differences at a climate system controller and determining a setpoint for one or more operating variables of one or more components of aclimate system in the building based on the sum of the differences.

In a further example of the foregoing, the step of determining the setpoints for the one or more operating variables is based on one or moretunable parameters.

In a further example of any of the foregoing, the method includes tuningthe one or more tunable parameters based on real-time dynamicinformation about the climate system.

In a further example of any of the foregoing, the current aspect of theclimate in the building is the current air temperature inside thebuilding. The set point for the aspect is a temperature set point.

In a further example of any of the foregoing, the one or more operatingvariables includes a temperature of conditioned air from an air handlingunit.

In a further example of any of the foregoing, the one of more componentsof the climate system include at least one of a chiller, a pump, and anair handling unit.

In a further example of any of the foregoing, the one of more operatingvariables includes a temperature of conditioning air from the airhandling unit.

A climate system for a building according to an exemplary embodiment ofthis disclosure, among other possible things includes a computing deviceconfigured to determine a difference between a current aspect of aclimate in a building and a set point for the aspect of climate in thebuilding for one or more zones in the building, sum the differences, anddetermine a set point for one or more operating variables of one or morecomponents of a climate system in the building based on the sum of thedifferences.

In a further example of the foregoing, the computing device is a climatesystem controller.

In a further example of any of the foregoing, the computing deviceincludes a first computing device configured to determine a differencebetween a current aspect of a climate in a building and a set point forthe aspect of climate in the building and sum the differences.

In a further example of any of the foregoing, the computing deviceincludes a second computing device configured to determine a set pointfor one or more operating variables of one or more components of aclimate system in the building based on the sum of the differences.

In a further example of any of the foregoing, the first computing deviceis a climate system controller and the second computing device is acontroller of the one or more components of the climate system.

In a further example of the foregoing, the computing device isconfigured to determine the set points for the one or more operatingvariables based on one or more tunable parameters.

In a further example of any of the foregoing, the computing device isconfigured to tune the one or more tunable parameters based on real-timedynamic information about the climate system.

In a further example of any of the foregoing, the real-time dynamicinformation about the climate system is provided to the computing deviceby one or more sensors in the building.

In a further example of any of the foregoing, the one or more componentsof the climate system includes at least one of a chiller, and pump, andan air handling unit.

In a further example of any of the foregoing, the current aspect of theclimate in the building is the current air temperature inside thebuilding. The set point for the aspect is a temperature set point.

In a further example of any of the foregoing, the one or more operatingvariables includes a temperature of conditioned air from an air handlingunit.

In a further example of any of the foregoing, the one or more componentsof the climate system includes at least one of a chiller, and pump, andan air handling unit.

In a further example of any of the foregoing, the one or more operatingvariables includes a temperature of conditioned air from an air handlingunit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a schematically shows a building with a climate system.

FIG. 1b schematically shows the building of FIG. 1a with multipleclimate zones.

FIG. 2 schematically shows a method for controlling the climate of thebuilding of FIGS. 1a -b.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an example climate system 20 for abuilding 18. The climate system 20 includes one or more chillers 22. Thechiller 22 can be any known type of chiller. Though one chiller 22 isshown in FIG. 1, it should be understood the climate system 20 caninclude more than one chiller 22. The chiller 22 includes a chillercontroller 24. The chiller 22 is operable to chill water for cooling thebuilding. One or more pumps 26 pump chilled water from the chiller 22 toone more air handling units 28 which utilize the chilled water to coolair for the building 18. Though one pump 26 and one air handling unit 28are shown in FIG. 1a , it should be understood that the climate system20 can include more pumps 26 and/or more air handling units 28. Forexample, the building 18 may include an air handling unit 28 on eachlevel. The pump 26 and air handling unit 28 also include controllers 30,32 (respectively). Though the example climate system 20 includes chiller22, pump 26, and air handling unit 28, other climate systems 20 caninclude other components as would be known in the art.

Each of the chiller 22, the pump 26, and the air handling unit 28 caninclude one or more electrical sub-components 36, as would be known inthe art. For instance, the air handling unit 28 can include one or moremotors, heat exchangers, dehumidifiers, etc. that enable the airhandling unit 28 to condition air, as are known in the art. Therespective controllers 24, 30, 32 are operable to control thesesub-components 36.

The climate system 20 also includes a climate system controller 34. Thechiller controller 24, pump controller 30, and air handling unitcontroller 32 are operable to communicate with the climate systemcontroller 34. The climate system controller 34 is also operable tocommunicate with an electrical power source, which is in some examplesanelectrical grid, and a thermal power source, such as a gas utility.The subcomponents 36 of the chiller 22, pump 26, and air handling units28 utilize electrical power and/or thermal power, and the climate systemcontroller 34 controls distribution of electrical/thermal power to thechiller 22, pump 26, and air handling units 28. The climate systemcontroller 34 is also operable to control the operation of the chiller22, pump 26, and air handling units 28 via their respective controllers24, 30, 32 to control the climate in the building 18. Each of thecontrollers discussed herein includes a computing device such as aprocessor and/or electronics which are programmed so that thecontrollers are operable to perform as discussed herein. Furthermore,the controllers discussed herein may include automatic PID (proportionalintegral derivative) capability, which utilizes a control loop feedbackmechanism to control processes and variables, as is known in the art.

FIG. 1b shows an example building 18 with three zones Zone 1, Zone 2,and Zone 3. Each zone includes an air handling unit 28 (AHU). In oneexample, the air handling units 28 in each zone acts in concert tocumulatively effect the temperature of air in the building 18. Inanother example, individual air handling units 28 serve their respectivezones of the building 18. A zone may be defined as a level of thebuilding 18, a room of a building 18, or in another way. In someexamples, each zone has its own climate requirements. The air handlingunits 28 in each zone are in communication with the climate systemcontroller 34. In this example, each zone has a temperature sensor 44and an interface 46 (discussed in more detail below).

Various aspects of the building 18 climate are affected by the climatesystem 34. For example, the temperature of air inside the building, thehumidity of air inside the building 18, the temperature of water in thebuilding 18, or other parameters as would be apparent to one of ordinaryskill in the art. Though the subsequent disclosure is made with respectto the temperature inside the building 18 for exemplary purposes, itshould be understood this disclosure is applicable to any aspect ofbuilding 18 climate.

With respect to the temperature inside the building 18, the air handlingunits 28 receive air from an air supply 38, which in some examples drawsor mixes air from outside the building 18. The air handling units 28condition (e.g., cool or heat) the air from the air supply 38 via thesub-components 36 such as heat exchangers as is known in the art. Forexample, a heat exchanger in the air handling units 28 can cool airusing cooled water provided by pump 26 from chiller 22 as discussedabove. As another example, a heat exchanger in the air handling units 28can heat air using thermal energy from the thermal energy source.

The air handling units 28 provide the conditioned air to the building 18via conduits 40 which are connected to vents 42 throughout the building18. The air handling unit controller 32 is configured to control itsrespective air handling unit 28 to provide a selected flowrate andtemperature to the building 18 via vents 42 to affect the temperature ofair inside the building 18 air. For instance, to cool air insidebuilding 18, the air handling unit 28 provides conditioned air that iscolder than the air inside the building 18. To heat air inside building18, the air handling unit 28 provides conditioned air that is hotterthan the air inside the building 18. The flowrate of conditioned airprovided by the air handling units 28 is inversely related to thetemperature, as will be discussed in more detail below.

More particularly, the building 18 has a selected air temperatureT_(selected) (also known as a set point). The set point can bepredetermined and programmed in to the air handling unit controllers 32and/or climate system controller 34. The set point can change over time.In some examples, a temperature is predetermined according to the timeof day. For instance, a temperature during times of building 18 highoccupancy can be predetermined to accommodate occupant comfort. Atemperature during times of low or no occupancy can be predetermined toreduce energy consumption of the climate system 20. In another example,the selected air temperature can be input by a user in the building 18via an interface 46, e.g., a thermostat, in the building 18, andcommunicated to the air handling unit controller 32 directly or via theclimate system controller 34. As shown in FIG. 2, in one example, eachzone includes an interface 46, and the interface 46 in each zone is incommunication with the air handling unit controller 32 in that zoneand/or the climate system controller 34. In another example, theselected air temperature is selected by the climate system controller 34based on occupant comfort requirements (either predetermined, inputted,or self-learned) and information from the electrical power source. Inyet another example, the set point is selected according to anycombination of the preceding examples. T_(selected) may vary in eachzone to accommodate the use of the individual zone and position in thebuilding (e.g. zones exposed to direct sunlight).

The building also has a current air temperature T_(current). The currentair temperature T_(current) can be provided directly to the climatesystem controller 34 from a temperature sensor 46 in the building 18. Asshown in FIG. 2, in one example, each zone includes a sensor 44, and thesensor 44 in each zone is in communication with the air handling unitcontroller 32 in that zone and/or the climate system controller 34.

The climate system controller 34 is configured to direct the airhandling unit controllers 32 to operate the air handling units 28 inorder to bring the current temperature in the building 18 T_(current)towards the temperature set point T_(selected) according to the method200, shown in FIG. 2. As discussed above, the air handling units 28 caneither act in concert or can act individually according to the climaterequirements of particular zones.

Turning now to FIG. 2, in step 202, the method 200 starts. In someexamples, the method 200 starts automatically, or without any userinput. In other examples, the method 200 can start at predeterminedtimes. In other examples, the method 200 can proceed continuously.

In step 204, the climate system controller 34 determines a differenceΔT_(i) between the temperature set point T_(selected) and a current airtemperature T_(current) in one or more zones of building 18. Dependingon the difference ΔT_(i), the climate system controller 34 determineswhether cooling or heating is required for each zone of building 18.

In step 206, the climate system controller 34 sums the ΔT_(i) for eachzone of the building 18 that requires heating to provide an aggregateΔT_(heat) for the building 18 according to Equation 1, where n_(heat) isthe number of zones in the building 18 that require heating:

${\Delta T_{heat}} = \frac{\sum\limits_{i = 1}^{n_{heat}}{\Delta \; T_{i}}}{n_{heat}}$

In step 206, the climate system controller 34 also sums the ΔT_(i) foreach zone of the building 18 that requires cooling to provide anaggregate ΔT_(cool) for the building 18 according to Equation 2, wheren_(cool) is the number of zones in the building 18 that require cooling:

${\Delta T_{cool}} = \frac{\sum\limits_{i = 1}^{n_{cool}}{\Delta T_{i}}}{n_{cool}}$

The aggregate ΔT_(heat) and ΔT_(cool) are related to anelectrical/thermal power demand for the building 18. That is, the largeraggregate ΔT_(heat) and ΔT_(cool), the more electrical/thermal powerwill be required to operate the components of the climate system 20 tobring the current temperature in the building (or in individual zones)18 T_(current) towards the temperature set point T_(selected).

Each component of the building 18 includes various outputs which havecontrollable variables. For instance, the air handling unit 28 outputsair, which has controllable variables of target conditioned airtemperature and flowrate. As another example, the chiller 22 outputscooled water, which has a controllable variable of cooled watertemperature. As a third example, the pump 26 outputs water, which has acontrollable variable of water pressure. The outputs also depend on theheating or cooling mode selected for the components in the zones of thebuilding 18. For instance, during warm months, the building 18components may be in a cooling mode that is associated with certainbuilding 18 components and their respective outputs/controllablevariables, and during cold months, the building 18 components may be ina heating mode that is associated with certain building 18 componentsand their respective outputs/controllable variables. In another example,the components may be configured to operate in multiple heating orcooling modes.

The direction from the climate system controller 34 can include thetarget set points for these variables. In another example, the directionfrom the climate system controller 34 includes information such that therespective controllers 24, 30, 32 can select the set points for thevariables based on the information.

For any variable V, the set point V_(sp) is defined at a time (t)according to Equation 3, where τ_(s) is sampling time, and K_(p) and αare tuneable parameters for optimizing control of the climate system 20.

${V_{sp}(t)} = {{V_{sp}\left( {t - 1} \right)} + \frac{{\Delta {T(t)}} - {\Delta {T\left( {t - 1} \right)}}}{\tau_{s}\alpha} + {\frac{K_{p}}{\alpha}\Delta {T(t)}}}$

In one example, the sampling time τ_(s) is selected according toEquation 4:

$\tau_{s} \geq \left\lceil {0.5\frac{V_{building}\rho}{\overset{.}{m\_ max}}} \right\rceil$

where m_{dot over (m)}ax is the maximum flowrate of air into thebuilding 18 from vents 42.

The parameter K_(p) is a proportional correction parameter, e.g., it isrelated to the amount of correction, or change, that will result inV_(sp) at time t as compared to V_(sp) at time t−1. In other words,K_(p) is related to the speed at which variable V is changed in order tobring the current temperature in the building 18 T_(current) towards thetemperature set point T_(selected). More particularly, K_(p) is relatedto an acceptable error for control of the building 18 climate. Ifoccupant discomfort is high, more error is acceptable, and K_(p) ishigher so that the amount of correction is larger, and in turn,T_(current) is more quickly brought towards the temperature set pointT_(selected). In this example, K_(p) is calculated according to Equation5:

$K_{p} = \frac{1 - \lambda}{\lambda*\tau_{s}}$

where λ is a parameter capturing the % error at steady-state for thebuilding 18 climate. For example, if an error of 5% is acceptable,λ=0.05. If less error is acceptable, λ is a lower value. However, inother examples, λ can be expressed as a first or second order model forerror, as is known in the art.

When occupant comfort is met, e.g., T_(current) is the same as or veryclose to T_(selected), the sampling time τ_(s) can be tuned, as will bediscussed in more detail below. The sampling time τ_(s) is definedaccording to Equation 6:

$\tau_{s} \geq \left\lceil {{0.5}\frac{V_{building}\rho}{\overset{.}{m\_ min}}} \right\rceil$

where V_(building), ρ, and m_{dot over (m)}in are know parametersrelated to the physical characteristics of building 18. V_(building) isthe total volume of the building 18, ρ is the density of air inside thebuilding 18, and m_{dot over (m)}in is the minimum flowrate of air intothe building 18 from vents 42.

As shown above in Equation 5, the parameter K_(p) depends on thesampling time τ_(s). Therefore, if a new sampling time τ_(s) is definedaccording to the tuning, a new parameter K_(p) can result as well.

In another example, τ_(s) is a continuously adaptive parameter that iscalculated continuously by the climate system controller 34 according toEquation 7:

$\tau_{s} \geq \left\lceil {{0.5}\frac{V_{building}\rho}{\overset{.}{m\_ measured}}} \right\rceil$

where m_me{dot over (a)}sured is the current delivered flowrate of airinto the building 18 from vents 42, which can be provided to the climatesystem controller via sensors or monitors at one or more of the vents34.

The parameter a is a sizing parameter that is applied so that thetemperature values in Equation 3 above are on at the same or similarorders of magnitude. For instance, ΔT(t) may be on the order of 0-5degrees Celsius, whereas V_(sp)(t) where the variable V is air handlingunit 28 output temperature is 20-30 degrees Celcius. In this example, αcan be selected to be 0.1.

In step 208, the set point for one or more variables V are determinedaccording to Equation 3. As discussed above, the set point for thevariable V can be determined by the climate system controller 34 andcommunicated to the controllers 24, 30, 32. In another example the setpoint for the variable V is determined by the controllers 24, 30, 32based on information from the climate system controller 34.

In step 210, the tuneable parameters K_(p) and a which are taken intoaccount for variable set point determination in Equation 3 are tuned inreal time using dynamic information about the climate system 20. Forinstance, new τ_(s) values are selected based on occupantcomfort/discomfort as discussed above, or updated as in Equation 7 abovebased on information from the sensors or monitors at vents 42. In turn,the parameter K_(p) can be updated when a new τ_(s) value is selected asdiscussed above. In one example, tuning is achieved by PID at thecontrollers 24, 30, 32, as discussed above. In a more particularexample, the PID control problem is in a velocity form, meaning that therate of change is explicitly taken into account.

The method 200 continuously performs step 208 as the tuneable parametersare tuned in step 210.

In step 212, the controllers 24, 30, 32 operate their respectivecomponents according to variable V set points to bring the currenttemperature in the building 18 T_(current) towards the temperature setpoint T_(selected).

The method 200 then returns to step 204.

The quantification of set points for variables V allows for fastresponse of the climate system 20 when a new temperature set pointT_(selected) is selected because the variable V set point is continuallyupdated as the method 200 repeats. As the climate system 20 operates,there may be a lag before T_(current) meets the temperature set pointT_(selected) as the T_(current) approaches the temperature set pointT_(selected). The continual updating of the variable V takes intoaccount this lag, and avoids overshooting the temperature set pointT_(selected). This in turn leads to more efficient use of theelectrical/thermal power by the climate system 20 and reduces thepossibility of occupant discomfort in building 18 (e.g., due to overshotfrom the desired temperature set point T_(selected)). Furthermore, otherthan defining the temperature set point T_(selected) in some examples(as discussed above) no other user input is required for tuning thecontrol of the climate system 20.

Furthermore, it should be understood that the preceding method isapplicable to control the climate system 20 to meet building set pointsother than temperature set point T_(selected). For example, thepreceding method can also be used to control the climate system 20 tomeet an air humidity set point, building air pressure set points,building water set points (e.g., temperature, flowrate, etc.), or otherset points.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this disclosure. The scope of legal protection given tothis disclosure can only be determined by studying the following claims.

What is claimed is:
 1. A method of controlling the climate of abuilding, comprising: determining a difference between a current aspectof a climate in a building and a set point for the aspect of climate inthe building for one or more zones of the building; summing thedifferences at a climate system controller; and determining a set pointfor one or more operating variables of one or more components of aclimate system in the building based on the sum of the differences. 2.The method of claim 1, wherein the step of determining the set pointsfor the one or more operating variables is based on one or more tunableparameters.
 3. The method of claim 2, further comprising tuning the oneor more tunable parameters based on real-time dynamic information aboutthe climate system.
 4. The method of claim 1, wherein the current aspectof the climate in the building is the current air temperature inside thebuilding and wherein the set point for the aspect is a temperature setpoint.
 5. The method of claim 4, wherein the one or more operatingvariables includes a temperature of conditioned air from an air handlingunit.
 6. The method of claim 1, wherein the one or more components ofthe climate system includes at least one of a chiller, and pump, and anair handling unit.
 7. The method of claim 2, wherein the one or moreoperating variables includes a temperature of conditioned air from theair handling unit.
 8. A climate system for a building, comprising: acomputing device configured to determine a difference between a currentaspect of a climate in a building and a set point for the aspect ofclimate in the building for one or more zones in the building, sum thedifferences, and determine a set point for one or more operatingvariables of one or more components of a climate system in the buildingbased on the sum of the differences.
 9. The climate system of claim 8,wherein the computing device is a climate system controller.
 10. Theclimate system of claim 8, wherein the computing device includes a firstcomputing device configured to determine a difference between a currentaspect of a climate in a building and a set point for the aspect ofclimate in the building and sum the differences.
 11. The climate systemof claim 10, wherein the computing device includes a second computingdevice configured to determine a set point for one or more operatingvariables of one or more components of a climate system in the buildingbased on the sum of the differences.
 12. The climate system of claim 11,wherein the first computing device is a climate system controller andthe second computing device is a controller of the one or morecomponents of the climate system.
 13. The climate system of claim 8,wherein the computing device is configured to determine the set pointsfor the one or more operating variables based on one or more tunableparameters.
 14. The climate system of claim 13, wherein the computingdevice is configured to tune the one or more tunable parameters based onreal-time dynamic information about the climate system.
 15. The climatesystem of claim 14, wherein the real-time dynamic information about theclimate system is provided to the computing device by one or moresensors in the building.
 16. The climate system of claim 8, wherein theone or more components of the climate system includes at least one of achiller, and pump, and an air handling unit.
 17. The climate system ofclaim 8, wherein the current aspect of the climate in the building isthe current air temperature inside the building and wherein the setpoint for the aspect is a temperature set point.
 18. The climate systemof claim 17, wherein the one or more operating variables includes atemperature of conditioned air from an air handling unit.
 19. Theclimate system of claim 8 wherein the one or more components of theclimate system includes at least one of a chiller, and pump, and an airhandling unit.
 20. The climate system of claim 19, wherein the one ormore operating variables includes a temperature of conditioned air froman air handling unit.